The invention relates to an electronic calculator and more particularly to an electronic calculator using a smaller number of input means than required in the past.
Hitherto, an electronic calculator (hereinafter referred to as "EC") has been widely accepted due to its compactness, light weight and ease of operation. Research and development have been conducted to render the electronic calculator more compact and inexpensive, leading to a prominent technical progress in this particular field. Where, however, the EC is used to carry out the four rules of arithmetic, presetting of any digit of 0 to 9 is effected by the corresponding presetting key.
The four modes of arithmetic operation, namely, addition, subtraction, multiplication and division are designated by operation of four arithmetic operation mode keys bearing the corresponding notations: +, -, .times. and .div.. Namely, the prior art EC is provided with keys denoting the respective digits of 0 to 9 and arithmetic operation mode keys. Provision of such large number of keys has obstructed the miniaturization of EC.
On the other hand, EC concurrently acting as a timepiece has been proposed in which part of a logic circuit included in the EC is used in common to that of an electronic timepiece. However, such timepiece-type EC requires not only keys for an EC but also those for a timepiece, necessarily increasing the number of keys. Particularly, the timepiece type EC should be rendered compact. With the prior art EC, however, the number of keys can not be prominently decreased, presenting difficulties in miniaturizing a timepiece type EC.